Addon object using PropertyGroup object attribute
Using annotations rather than class properties
It is now defined as an annotation. They are added to a key value dictionary __annotations__ on the class on which they are defined. Try something like
TestProp.__annotations__[&quot;my_float_prop&quot;]

There is a generic Namespace class where can
from argparse import Namespace
props = Namespace(**TestProp.__annotations__)

and then access them via
props.test_float_prop 

Consider too using math.pi.